Motor powered air hammer



MaY23, 1967 G. J. BENUSKA ETAL 3,321,033

MOTOR POWERED AIR HAMMER Filed Feb. 3, 1965 NM 3N mw G NN QN mw WMS. MN(

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NNN www tSw Sm RQ khl United States Patent O 3,321,033 MTR PGWERED AIR HAMMER George J. Bennslra, Bolton, and Ted Henry, Downers Grove, Ill., assignors, by mesne assignments, to Standard Alliance Industries, Inc., Chicago, Ill., a corporation of Illinois Filed Feb. 3, 1965, Ser. No. 429,958 7 Claims. (Cl. 173-419) In the past numerous diffe-rent devices have been em-` ployed in these operations including steam or diesel powered pile drivers, mechanically operated portable drop hammers, swinging frost balls, spring actuated hammers,

and various types of pneumatic tools, and these have been inadequate for `various reasons including unduly complex designs involving expensive fuel pumps, nozzles and valves, inability to operate in various different positional orientations, diiiiculty in adjustment of the impact level, and unduly expensive and bulky auxiliary equipment such as steam boilers and steam lines in the case of steam powered pile drivers.

The principal object of the invention is to provide an improved motor powered air hammer characterized by a simple and rugged design that lends itself to portability and to quick attachment and detachment to a power source.

Another object of the invention is to provide a motor powered air hammer employing an adjustable air pressure system to enable accurate adjustment and control of the impact level.

A further object of the invention is the provision of a motor powered air hammer of compact form that may be connected to the hydraulic system of `conventional hydraulic excavator equipment and that may be mounted to the boom of the excavator for ease in transporting the device. i

Still another object of the invention is the provision of a motor operated air hammer having a minimum of parts and eliminating fatigue failure such as is usually associated with equipment where high stresses are repeatedly applied.

Other objects and advantages of the present invention will be apparent from the following description and claims, and are illustrated in the accompanying drawings which show structure embodying preferred features of the present invention and the principles thereof, and what is now considered to be the best mode in which to apply these principles.

In the accompanying drawings forming a part of this specification, and in which like numerals are employed to designate like parts throughout the same,

FIG. l is a side elevational view of a motor powered air hammer constructed in accordance with this invention, with parts of the drive housing broken away and sectioned along the line 1--1 of FIG. 2 to facilitate disclosure;

FIG. 2 is a lengthwise sectional view through the unit .and includes a diagrammatic representation `of a pressurized air system which is employed to establish and en- -able adjustment of the impact level developed by the tool; and

ICS

PIG. 3 is a transverse sec-tional view through the drive housing and is taken as indicated on the line 3 3 of FIG. 1.

Referring now to the drawings, the overall arrangement of the impact tool of this invention includes an elongated main slide ba-rrel 10 having an anvil guide housing 11 fixed thereto at one end in endwise alignment therewith and having a drive housing 12 fixed at its other end and also arranged in endwise alignment with the barrel. The barrel 10 has integral end anges 10F, one being in bolted assembly to an integral end dan-ge 11F provided on the anvil guide housing 11 and the other being in bolted assembly directly to the drive housing 12. An anvil shaft 13 is carried in the anvil guide housing 11 and projects endwise therethrough to contact the material to be impacted. The anvil shaft 13 is formed with an integral anvil cup 1=3C of enlarged form which is iitted with a cushion insert 14 of brass 0r lead, and a ring 115 of resilient material such as molded urethane rubber is disposed between the anvil 13C and the reduced lower end 11fE of the anvil guide housing 111 to function as a shock absorber. These cushioning facilities associated with the anvil 11 prevent severe shock eifects between hard metal parts and minimize failure problems under heavy duty loading cycles.

In the preferred form illustrated herein, a hammer shaft 15 is reciprocably slidable through the barrel 10 and through the drive housing 12 and is operable to apply endwise impacts to the anvil shaft 13, such impacts being transmitted through the cushion insert 14 that is nested in the anvil cup 13C. The upper portion 15R of the hammer shaft extends through the drive housing 12 and is of reduced diameter to receive a case hardened steel retainer sleeve 1:6 and a steel T-bar head .17 located to occupy an intermediate region of the drive housing 12. A lower guide bearing 1=8 is illustrated as being provided integral with the drive housing 12 to seat in the upper end of the barrel 10 and an upper guide bearing 19 is mounted to the upper end wall 12U of the guide housing and is encased by means of a cover housing 20. The guide bearings 18 and 19 provide balanced bearing support for guiding the movement of the hammer shaft assembly which comprises the hammer shaft 15, the sleeve 16 and the T-head 17. The upper end of the hammer shaft 15 is threaded as indicated at 15T and receives a lock nut 21 to hold the sleeve 16 and T-bar :17 in fixed position with the sleeve 16 riding against the upper guide bearing 19 and with the main hammer shaft 15 riding in the lower guide bearing 18.

In accordance with this invention an air `spring is incorporated in the tool by providing a compression chamber 22 within the upper end of the barrel 10'. For this purpose O-ring seals 23 and 24, respectively, are provided to complete a seal between the barrel 10 and the drive housing 12 and between the lower guide bearing 18 and the hammer shaft 15. In addition, the lower guide bearing 18 is equipped at its upper end with an oil seal 25 and thus the lower guide bearing serves as a stationary end cap or end wall defining one limit of the compression chamber 22. To `complete the compression chamber,` a piston 26 which may be of alloy steel is mounted in loose but stable relation upon an enlargement 15E near the lower end of the hammer shaft 15. Teon seal rings 27 and 28, respectively, are employed to complete the seal between the piston 26 and the slide barrel 10 and between the piston 26 and the hammer shaft 15. While the piston has a floating relation on the hammer shaft, the mounting configuration of these parts in a pressurized chamber is such that the piston 26 normally maintains a fixed relationship to the shaft 15 during shaft movement in either direction. A cushion ring 29 of molded urethane rubber encircles the lower end of the hammer D shaft and a keeper plate 30 in the form of a steel ring retains this cushion ring, with the keeper plate 30 being seated against an internal peripheral shoulder S provided within the barrel, and the keeper plate, in turn, being locked in place by a Isplit ring 3GR that nests in a lock groove provided in the slide barrel.

Finally, another cushion ring 32 of molded urethane rubber is provided to encircle the hammer shaft on the llower side of the keeper plate 30 and a second keeper plate 33 in the form of a steel ring is provided within the extreme lower end of the slide barrel 10 to be positioned between the second cushion ring 32 and an annular internal shoulder 11S that is provided on the anvil guide housing 11.

The compression chamber 22 of the air spring has an inlet port 34 which is illustrated as a side wall opening of the slide barrel to receive an air feed line 35 leading from a pressurized tank or air accumulator 36 which may typically have air stored under a pressure of 10() p.s.i. This air feed line 35 has an adjustable pressure reducing valve 37 and a check valve 38 to accommodate one-way infeed ow of air to the compression chamber 22. The pressure valve of the air fed to the compression chamber 22 may be selected at any value Within the limit established by the accumulator and, by way of example, in a typical operating situation, a value of p.s.i. may be employed.

One of the important features of this invention is that by simple adjustment of the pressure reducing valve 37, the minimum pressure maintained within the compression chamber 22 is accordingly adjusted, thereby determining the energy storage capacity of the compression chamber 22 and correspondingly, the impact energy level of the tool, all without need for varying the stroke length. Thus, adjustment of the operating energy level of the tool requires no complicated mechanisms within the tool itself, and this simplifies its construction and leads to a more durable, longer-lived tool.

Since a constant stroke arrangement simplifies the drive system, numerous types of drives will occur to those skilled in this art for eecting repeated retraction and release of the hammer shaft 15. For purposes of illustrative disclosure, however, a preferred drive arrangement is illustrated herein wherein the T-bar head 17 is employed to present a pair of abutments 17A which are located in flanking relation to the hammer shaft 15. A spur gear shaft `40l is disposed crosswise in the drive housing 12 and has its opposite ends journalled in wall mounted bearings 41 carried by the drive housing. A pair of spur gears 42 are keyed to the spur gear shaft 40 in spaced relation to flank the hammer shaft 15. Each of these spur gears 42 rotatably supports a pair of heavy cam vrollers 43 symmetrically positioned on a diametral line through the axis of the spur gear shaft 40. The spur gears 42 and their cam rollers 43 are mounted to operate in unison in engaging the abutments 17A presented by the T -head.

A pinion shaft 44 extends crosswise in spaced parallel relation to the spur gear shaft 40 and has its ends journalled in wall mounted bearings 45 carried by the drive housing. The pinion 'shaft 44 is equipped With a pair of pinion gears 46 spaced to mesh with corresponding ones of the spur gears 42 for driving the same in uniformly timed relation. The pinion shaft 44 is, in turn, equipped with a worm gear 47 which is preferably integral. A motor 48 is shown mounted outboard on the drive housing 12 in FIG. 1 and the motor shaft 48S is represented in FIG. 3 and as shown therein is coupled to a worm shaft 49 which, in turn, drives the worm gear 47 on the pinion shaft, and through the pinion gears 46 drives the spur gears 42. trated herein, a total gear reduction ratio of 60 to 1 is provided.

In FIGS. 1 and 2 the hammer shaft 15 and its 'T-bar head 17 are shown in the start or down position,

In the preferred form illusand in FIGS. 2 and 3 the cam roll bearings 43 are shown in the position wherein the T-head 17 is about to be picked up at the beginning of the retraction stroke.

In FIG. l, for purposes of illustration, the cam rollers 43 are shown at an intermediate position wherein the left hand cam rollers have released the T-head and the power stroke has been completed but the right hand cam rollers have not yet picked up the T-head for retracting the hammer shaft.

FIG. 2 illustrates in phantom lines the maximum lift position for the T-head 17 and for the pair of cam roll bearings 43. Further rotation of the spur gears in the direction of the arrow shown thereon in FIG. 2 will move the phantom line cam roll bearing 43 free of the T-head 17 and at this time the stored energy inthe air spring will act against the pistion and drive the hammer shaft through its power stroke and into impacting relation against the anvil 13 which will, at this time, be spaced above the shock absorber ring 15 against which it bottoms at the end of the power stroke. It should be noted that a single cam roller 43 upon each spur gear is sufficient but the use of two doubles the cycle rate of operation and eliminates dead time from the operating cycle.

In the preferred form, the motor 48 is of any suitable hydraulic type, it being contemplated that the unit may be mounted on the boom of any hydraulic excavator having :a hydraulic system capable of providing a iiow capacity in the range from 20 gallons per minute to 50 gallons per minute at 1500 p.s.i. or greater. If desired or appropriate, an electric motor may be substituted.

For the illustrated arrangement, the top dead center position for the piston is indicated by the dashed line 50 appearing in FIG. 2 and this provides a compression ratio for the air spring of 6 to 1. Exhaust ports 51 are shown in the side walls of the barrel to facilitate rapid power travel of the hammer shaft, with these exhaust ports 51 being covered and sealed by the piston 26 when ythe tool is at its start position as illustrated in the drawings.

Thus, while preferred constructional features of the invention are embodied in the structure illustrated herein, it isl to be understood that changes and variations may be made by those skilled in the art without departing from the spirit and scope of the yappended claims.

What is claimed is:

1. A motor powered pneumatic impact tool comprising a main slide barrel having anvil guide housing structure at one end, an anvil shaft carried in said anvil guide housing structure and projecting therethrough, a hammer shaft reciprocably slidable through said barrel to apply endwise impacts to said anvil shaft, means defining a compression chamber within said barrel and including a piston xedly mounted on said hammer shaft to operate in sealing slidable relation in said barrel and means completing an air seal -at the other end of the barrel, means for supplying air to said compression chamber to maintain a predetermined minimum pressure therein, a motor mounted in fixed relation to said barrel, and mechanical means connecting said motor and operable repeatedly rst to shift said hammer shaft to move said piston towards said other end of the barrel for multiplying pressure in said compression `chamber and thereafter to release said hammer shaft to enable expansion of said chamber to drive the hammer shaft against vthe anvil shaft, said means for supplying air comprising an air accumulator for storing air at a predetermined pressure level above atmospheric pressure, adjustable pressure reducing means interconnected between said air accumulator and said compression chamber for supplying air to said compression chamber at a selected pressure level below said predetermined Iair accumulator pressure level, and a one way Valve interconnected between said adjustable means and said compression chamber to permit flow of air into said compression chamber while preventing increased pressure in said compression chamber during compression from influencing said adjustable means.

2. A motor powered pneumatic impact tool comprising a main slide barrel having anvil guide housing structure at one end, an anvil shaft carried in said anvil guide housing structure and projecting therethrough, a hammer shaft reciprocably slidable through said barrel to apply endwise impacts to said anvil shaft, means defining a compression chamber Within said ybarrel and including a piston xedly mounted on said hammer shaft to operate in sealing slidable relation in said b-arrel and means completing an air seal at the other end of the barrel, a source of air under pressure external of said barrel, adjustable pressure reducing means for supplying air from said source to said compression cham-ber to maintain a predetermined minimum pressure therein, said source of air comprising an air accumulator for storing lair at a predetermined pressure level above atmospheric pressure, said adjustable pressure reducing means being interconnected between said air accumulator and said compression cham- =ber and supplying air to said compression chamber at a selected pressure level below said predetermined air accumulator pressure level, and a one Way valve interconnected between said adjustable means and said compression chamber to permit the ow of air into said compression chamber while preventing increased pressure in said compression chamber during compression from inuencing said adjustable means, a motor mounted to fixed relation to said barrel, and mechanical means connecting said motor and operable repeatedly first to shift said hammer shaft to move said piston towards said other end of the barrel for multiplying pressure in said combustion chamber and thereafter to release said hammer shaft to enable expansion of said lchamber to drive the hammer shaft against the anvil shaft.

3. A motor powered pneumatic impact tool comprising a main slide barrel having anvil guide housing structure at one end and drive housing structure at the other end, an anvil shaft carried in said anvil guide housing structure and projecting therethrough, a hammer shaft reciprocably slidable through said ybarrel to apply endwise impacts to said anvil shaft, said hammer shaft projecting into said drive housing structure from the other end of said barrel, means defining a compression chamber within said barrel and including a piston fixedly mounted on said hammer shaft to operate in sealing slidable relation in said barrel and end cap be-aring means at the other end of the barrel and guiding said hammer shaft to complete an air seal for said compression chamber, a source of air under pressure external of said barrel, adjustable pressure reducing means for supplying air from said source to said compression chamber to maintain a predetermined minimum pressure therein, said source of air comprising an air accumulator for storing air at predetermined pressure level above atmospheric pressure, said adjustable pressure reducing means being interconnected between said air accumulator and said compression chamber and supplying air to said compression chamber at a selected pressure level below said .predetermined air accumulator pressure level, `and a one Way valve interconnected between said adjustable means and said compression charnber to permit the ow of air into said compression chamber While preventing increased pressure in said compression chamber during compression from influencing said adjustable means, a motor mounted in fixed relation to said drive housing structure and mechanical means within said drive housing structure to be driven by said motor and operably connected repeatedly first to shift said hammer shaft to move said piston towards said other end of the barrel for multiplying pressure in said combustion chamber and thereafter to release said hammer shaft to enable expansion of said cham-ber to drive the hammer shaft against the anvil shaft.

4. A -motor powered pneumatic impact tool comprising a main slide barrel having anvil guide housing structure at one end 'and drive housing structure at the other end, an -anvil shaft carried in said anvil guide housing structure and projecting endwise therethrough, a hammer shaft reciprocably slidably carried in said drive housing structure and projecting through said barrel to apply endwise impacts to said anvil shaft, means defining a compression chamber within said Vbarrel and including a piston ixedly mounted on said hammer shaft to operate in sealing slidable relation in said barrel and end cap bearing means in said other end of the barrel to guide said hammer shaft and complete an end seal for said chamber, a source of air under pressure external of said barrel, adjustable pressure reducing means connected to supply air from said source to said chamber to maintain a predetermined minimum pressure therein, said source of air comprising an air accumulator for storing air at a predetermined pressure level above atmospheric pressure, said adjustable pressure reducing means being interconnected between said air accumulator and said compression chamber and supplying air to said compression chamber at a selected pressure level below said predetermined air accumulator pressure level, and a one Way valve interconnected between said adjustable means and said compression chamber to permit the liow of air into said compression chamber while preventing increased pressure in said compression chamber during compression from influencing said adjustable means, said hammer shaft having abutment means carried rigidly at a portion thereof that is `within said drive housing structure, a motor mounted to said drive housing structure and having a drive shaft rotatable therein, cam means mounted in said drive housing structure and connected to be cyclically driven yby said drive shaft to repeatedly establish one way shifting movement of said abutment means and thereby retract the hammer shaft a predetermined distance from said anvil shaft from multiplying pressure in said chamber and enable expansion of said chamber to drive the h-ammer shaft against the anvil shaft.

5. A motor powered pneumatic impact tool comprising a main slide barrel having anvil guide housing structure at one end and drive housing structure at the other end, an anvil shaft carried in said anvil guide housing structure 'and projecting endwise therethrough, a hammer shaft reciprocably slidably carried in said drive housing structure and projecting through said barrel to apply endwise impacts to anvil shaft, means defining a compression chamber within said barrel and including a piston xedly mounted on said hammer shaft to operate in sealing slidable relation in said barrel and end cap bearing means in said other end of the ybarrel to guide said hammer shaft and complete an end seal for said chamber, a source of air under pressure external of said impact device, adjustable pressure reducing means external of said impact device connected to supply air from said source to said chamber to maintain a predetermined minimum pressure therein, said barrel having an exhaust port opening therethrough and normally covered by said piston when said chamber is fully expanded, said hammer shaft at a portion thereof that is within said drive housing structure having a T-bar configuration constituting a pair of abutment means, a motor mounted to said drive housing structure and having a drive shaft rotatable therein, a pair of cam roller means mounted eccentrically on a pair of drive gears that are journalled in said drive housing structure and are connected through gear reduction means disposed in said drive housing structure to be cyclically driven by said drive shaft to repeatedly establish one way shifting movement of said cam roller means against said abutment means and thereby retract the hammer shaft a predetermined distance from said anvil shaft for multiplying pressure in said chamber and enable expansion of said chamber to drive the hammer shaft against the anvil shaft, said hammer shaft having resilient means at the opposite end of said T-bar coniiguation to act as a shock absorber, said resilient means comprising a plurality of non-contiguous members of high shock absorptive material.

6. A motor powered pneumatic impact tool comprising a main slide barrel, a hammer shaft reciprocably slidable through said barrel to apply endwise impacts through one end of the slide barrel, means defining a compression chamber within said barrel and including a piston xedly mounted on said hammer shaft to operate in sealing slidable relation in said barrel and means completing an air seal at the other end of the barrel, means for supplying air to said compression chamber to maintain a predetermined minimum pressure therein, a motor mounted in fixed relation to said barrel, and mechanical means connecting said motor and hammer shaft and operable repeatedly first to shift said hammer shaft to move said piston tow-ards said other end of the 4barrel for multiplying pressure in said combustion chamber and thereafter to release said hammer shaft to enable expansion of said chamber to drive the hammer shaft through a power stroke, said means for supplying -air comprising an air accumulator for storing air at a predetermined pressure level above atmospheric pressure, .adjustable pressure reducing means interconnected between said air accumulator and said compression chamber for supplying air to said compression chamber'at a selected pressure level ybelow said predetermined air accumulator pressure level, and a one Way valve interconnected between said adjustable means and said compression chamber to permit flow of air into said compression chamber while preventing increased pressure in said compression chamber during compression from inuencing said adjustable means.

7. A motor powered pneumatic impact tool comprising a main slide barrel, a hammer shaft reciprocably slidable through said barrel to apply endwise impacts through one end of the slide barrel, means defining a compression chamber within said barrel and including a piston fixedly mounted on said hammer shaft to operate in sealing relaf5 tion in said barrel and means completing an air seal at the other end of the barrel, a source of air under pressure external of said barrel, adjustable pressure reducing means for supplying air from said source to said compres- 5 sion chamber to maintain a predetermined minimum pressure therein, said source of air comprising an air accumulator for storing air at a predetermined pressure level above atmospheric pressure, said adjust-able pressure reducing means being interconnected between said air accumulator and said compression chamber and supplying air to said compression chamber at a selected pressure level below s-aid predetermined air accumulator pressure level., 'and a one way valve interconnected between said adjustable means and said compression chamber to permit the flow of air into said compression chamber while preventing increased pressure in said compression chamber during compression from influencing said adjustable means, a motor mounted in fixed relation to said barrel, and mechanical means connecting said motor and hammer shaft and operable repeatedly rst to shift said hammer shaft to move said piston towards said other end of the barrel for multiplying pressure in said combustion chamber and thereafter to release said hammer shaft to ena'ble eXpansion of said chamber to drive the hammer shaft through a power stroke.

References Cited by the Examiner UNITED STATES PATENTS 2,668,518 2/1954 White 173-169:

2,722,918 11/1955 Kimball 173-136 2,776,539 1/1957 Pearson 173--123 3,244,241 4/1966 Ferwerda 173--119 3,250,334 5/1966 Sussman 173--116 FRED C. MATrERN, JR., Primary Examiner.

L. P. KESSLER, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,321, 033 May 23, 1967 George-J. Benuska et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 28, for "to" read in column 6, line 46, before "anvil" insert said Signed and sealed this 21st day of November 1967.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. A MOTOR POWERED PNEUMATIV IMPACT TOOL COMPRISING A MAIN SLIDE BARREL HAVING ANVIL GHIDE HOUSING STRUCTURE AT ONE END, AN ANVIL SHAFT CARRIED IN SAID ANVIL GUIDE HOUSING STRUCTURE AND PROJECTING THERETHROUGH, A HAMMER SHAFT RECIPROCABLY SLIDABLE THROUGH SAID BARREL TO APPLY ENDWISE IMPACTS TO SAID ANVIL SHAFT, MEANS DEFINING A COMPRESSION CHAMBER WITHIN SAID BARREL AND INCLUDING A PISTON FIXEDLY MOUNTED ON SAID HAMMER SHAFT TO OPERATE IN SEALING SLIDABLE RELATION IN SAID BARREL AND MEANS COMPLETING AN AIR SEAL AT THE OTHER END OF THE BARREL, MEANS FOR SUPPLYING AIR TO SAID COMPRESSION CHAMBER TO MAINTAIN A PREDETERMINED MINIMUM PRESSURE THEREIN, A MOTOR MOUNTED IN FIXED RELATION TO SAID BARREL, AND MECHANICAL MEANS CONNECTING SAID MOTOR AND OPERABLE REPEATEDLY FIRST TO SHIFT SAID HAMMER SHAFT TO MOVE SAID PISTON TOWARDS SAID OTHER END OF THE BARREL FOR MULTIPLYING PRESSURE IN SAID COMPRESSION CHAMBER AND THEREAFTER TO RELEASE SAID HAMMER SHAFT TO ENABLE EXPANSION OF SAID CHAMBER TO DRIVE THE HAMMER SHAFT AGAINST THE ANVIL SHAFT, SAID MEANS FOR SUPPLYING AIR COMPRISING AN AIR ACCUMULATOR FOR STORING AIR AT A PREDETERMINED PRESSURE LEVEL ABOVE ATMOSPHERIC PRESSURE, ADJUSTABLE PRESSURE REDUCING MEANS INTERCONNECTED BETWEEN SAID AIR ACCUMULATOR AND SAID COMPRESSION CHAMBER FOR SUPPLYING AIR TO SAID COMPRESSION CHAMBER AT A SELECTED PRESSURE LEVEL BELOW SAID PREDETERMINED AIR ACCUMULATOR PRESSURE LEVEL, AND A ONE WAY VALVE INTERCONNECTED BETWEEN SAID ADJUSTABLE MEANS AND SAID COMPRESSION CHAMBER TO PERMIT FLOW OF AIR INTO SAID COMPRESSION CHAMBER WHILE PREVENTING INCREASED PRESSURE IN SAID COMPRESSION CHAMBER DURING COMPRESSION FROM INFLUENCING SAID ADJUSTABLE MEANS. 